1. Field of the Invention
The present invention relates to a communications interface that enables wireless-communication headsets, or the like, to be used with various types of communications systems, without the need to modify the headsets or the communications system in use.
2. Description of the Background Art
Various types of portable communications devices are available to facilitate communication between field personnel and a central location. For example, during rocket launches, numerous personnel are stationed around the launch pad and they must be able to participate in voice communications from a command center. The personnel typically use centralized communications equipment for voice conferencing, portable radios or telephones for this purpose. Two types of portable radios or telephones are particularly suited for such an environment, these being wireless and hard wired communication headsets. In both cases, the units are wearable by the users so that the users can keep their hands free most or all of the time. Generally, wired headsets have a push-to-talk (PTT) device built-in that provides certain communications equipment with a keying signal during transmit. Thus, while a user can continuously hear the communications of others using the system, they must actuate a push button, or the like, when they want to talk on the system. This arrangement is especially desirable where a large number of users are communicating on a single channel, and substantially reduces extraneous background and other noise that would otherwise impede the clarity of the communications.
However, the cords from wired headsets physically cause problems, especially around sensitive flight hardware. Although this problem is solved by wireless headsets, known commercial off-the-shelf (COTS) wireless-communication headsets operate (transmit and receive) continuously, and are not designed to provide any special signaling such as PTT, or external xe2x80x9coff hookxe2x80x9d or xe2x80x9con hook.xe2x80x9d PTT information, for example, is required by many communications systems (especially modern digital systems) to trigger events in the system when the user xe2x80x9ckeys upxe2x80x9d to participate in a voice conference or network, thus making continuous transmission wireless headsets incompatible with such systems.
Continuous transmission impacts analog and digital voice systems differently. In analog systems, amplifiers are continuously active which results in excessive power usage. In addition, inopportune noise is introduced into the voice networks by COTS wireless headsets interfaced to the networks. In digital systems, the operation of the central equipment is impacted while a switch in the equipment considers a wireless headset user as a xe2x80x9ccontinuous talkerxe2x80x9d into the voice networks. Further, non-PTT communications devices are not even permitted to be used with some communication systems, such as those in use by Department of Defense agencies, law enforcement and public safety (including 911) call centers, air traffic controller operations environments, other mission critical communications environments and even commercial (telemarketing) call centers. In view of the desirability of using wireless headset type communications devices, a need therefore exists for enabling these devices to be used in applications requiring PTT or other signaling.
The present invention fulfills the foregoing need through provision of a universal interface adapter circuit that can, for example, interface a COTS wireless communications headset with any type of communications system, including those that require PTT or any other type of signaling. The interface adapter circuit is comprised of several main components, including an RF signaling receiver, and a decoder and control signal generator, that are preferably implemented with a microcontroller, for decoding signals received from the signaling receiver and processing the decoded signals. A programmable or configurable impedance matching and interfacing circuit is also provided for interfacing a COTS headset system base to a communications system. A signaling transmitter, which is preferably portable (e.g., handheld), is employed by the wireless headset user to send encoded signals to the signaling receiver. The signaling transmitter is preferably a low-power auxiliary radio transmitter that is in addition to the radio transmitter of the headset. This permits any one of a number of COTS brands and styles of headsets to be used with the invention interchangeably.
In an embodiment of the invention directed specifically to PTT signaling, the wireless headset user presses a button on the signaling transmitter when they wish to speak. This sends an encoded signal to the microcontroller that decodes the signal and recognizes the signal as being a PTT request. In response, the microcontroller generates a control signal that actuates a relay to close a switch and complete a voice connection between the headset system base and the communications system so that the user can communicate with the communications system. With this arrangement, the COTS wireless headset can be interfaced to any communications system that requires PTT signaling, without modification of a commercial headset device, or selection of a specific commercial wireless headset device. In addition, the interface adapter circuit can also or alternately be configured to respond to or deliver any other types of signals, such as dual-tone-multiple-frequency (DTMF) tones, and on/off hook signals. The present invention also permits multiple wireless users to operate independently in the same environment through use of a plurality of the interface adapter circuits.